TORONTO — Even two hours before the first pitch, time Oakland Athletics manager Bob Melvin sensed the different atmosphere in the ballpark as he sat in the dugout at the Rogers Centre.

The reason for the buzz was the major league debut of Vladimir Guerrero Jr., the 20-year-old son of Hall of Famer Vladimir Guerrero and the No. 1 rated prospect in baseball.

“A lot of hoopla out here,” Melvin said. “I walked out, and it almost looked like a playoff game.”

But on this night, not so good for the A’s. Guerrero led off the bottom of the ninth inning with his first major league hit, a double to right field against Yusmeiro Petit.

Billy McKinney sacrificed pinch runner Alen Hanson to third and, after Teoscar Hernandez lined out, Brandon Drury hit his third homer of the season and the first walk-off homer of his career and the Blue Jays won 4-2.

It undid a nice comeback by the A’s, who tied the game on a two-run, pinch-hit homer by Robbie Grossman in the top of the eighth against reliever Joe Biagini.

Now the A’s, who could not lose to the Blue Jays in seven games last season, have not been able to beat Toronto in four games this season, including three in Oakland last weekend.

The A’ still have not been able to figure out Toronto starter Marcus Stroman, who pitched into the ninth inning of a 5-1 win on April 19. This time he held the A’s to one hit and two walks while striking out seven in seven scoreless innings.

“He’s got a good slider,” Melvin said. “When he’s pitching well, that’s his pitch. He’s just in enough to get us off that, just enough fastballs on the outside corner to extend off the slider, and when he needed to throw a strikeout with the slider, he did it as well.”

The A’s had solid start from Mike Fiers, who allowed six hits — including a solo homer by Eric Sogard — and two runs in seven innings. He struck out five and did not allow a walk in becoming the first Oakland starter to last seven innings this season.

“I thought he was a lot better today,” Melvin said. “He gave up the home run right away and the only other one run was kind of a broken-bat single to center. So he located better, looked like he pitched with a lot more confidence even after getting off to a rough start with the home run, and he was economical with his pitches, got us deep in the game.”

The home run Fiers allowed to lead off the first was the sixth he has given up his past four starts.

“I’ve been feeling really good actually the past couple starts,” Fiers said. “I’ve just been making mistakes and teams are kind of capitalizing. So I didn’t really put too much emphasis on the score or how many runs I gave up last time, just attack it and throw my pitches, and pitch how I pitch. Try to keep them off balance and make big pitches when I need to.”

Fiers said facing Guerrero, who was being cheered at every move by the announced crowd of 28,688, like facing “just another guy.”

Left fielder Chad Pinder did make an excellent catch at the wall on a drive in the fourth inning by Guerrero, who went 1 for 4.

In the ninth, Pinder almost put one out himself against Ken Giles on a double that hit the top of the left-field wall.

“That’s not a surprise to us anymore,” Melvin said of Pinder’s catch. “And talk about a game of inches. That ball he hits, if it’s another two inches, (Blake) Treinen’s in the game and we’re ahead. So unfortunately had a little too much topspin on it.”

More in Sports

New weekly feature on the Hotline, planned for Sunday mornings. Please note: 1. The selections for players of the week will be the same as those I submit to the conference office Sunday night/Monday morning for the weekly awards voting. 2. There will be exceptions, but I give significant weight to the quality of competition when evaluating and comparing performances....

Insta-reaction to Pac-12 developments on and off the field ... (Our Best of the Week honorees are here). 1. Rendering judgment. The Hotline was clear as we could be: Week Three was momentous for the conference, not only because of the opponents but also the stages. As we discussed in detail Friday, the Pac-12 had six games on full-reach TV...